Physical parameters of highly injected silicon in the modeling of concentrator solar cells

For several years, high-resistivity solar cells have been modeled successfully at Stanford using an ambipolar Auger coefficient, C_a=1.66×10^-30 cm⁶/s, and an ambipolar diffusion constant, D_a=18 cm²/s. Recently, these assumptions have been questioned, and the possibility of carrier-induced bandgap narrowing was introduced. When this was done, the dramatically different values of C_a=3.88×10^-31 cm⁶/s and D_a=9 cm²/sec were used to fit the experimentally observed performance of point-contact solar cells. A number of experiments have been performed, and it was determined that below n=2×10¹⁷/cm³, C_a=1.66×10^-30 cm⁶/s and D_a=17 cm²/sec. The remaining discrepancies between the experimental cell data and the cell modeling are discussed